It is well documented that certain individuals, including elderly and post-surgical patients, are at a heightened risk of falling. There are many reasons for this but, broadly speaking, these individuals are often afflicted by gait and balance disorders, weakness, dizziness, confusion, visual impairment, and postural hypotension (i.e., a sudden drop in blood pressure that causes dizziness and fainting), all of which are recognized as potential contributors to a fall. Additionally, cognitive and functional impairment, and sedating and psychoactive medications are also well recognized risk factors.
A fall places the patient at risk of various injuries including sprains, fractures, and broken bones--injuries which in some cases can be severe enough to eventually lead to a fatality. Of course, those most susceptible to falls are often those in the poorest general health and least likely to recover quickly from their injuries. In addition to the obvious physiological consequences of fall-related injuries, there are also a variety of adverse economic and legal consequences that include the actual cost of treating the victim and, in some cases, caretaker liability issues.
In the past, it has been commonplace to treat patients that are prone to falling by limiting their mobility through the use of restraints, the underlying theory being that if the patient is not free to move about, he or she will not be as likely to fall. However, research has shown that restraint-based patient treatment strategies are often more harmful than beneficial and should generally be avoided--the emphasis today being on the promotion of mobility rather than immobility. Among the more successful mobility-based strategies for fall prevention include interventions to improve patient strength and functional status, reduction of environmental hazards, and staff identification and monitoring of high-risk hospital patients and nursing home residents.
Of course, monitoring high-risk patients, as effective as that care strategy might appear to be in theory, suffers from the obvious practical disadvantage of requiring additional staff if the monitoring is to be in the form of direct observation. Thus, the trend in patient monitoring has been toward the use of electrical devices to signal changes in a patient's circumstance to a care-giver who might be located either nearby or remotely at a central monitoring facility, such as a nurse's station. The obvious advantage of an electronic monitoring arrangement is that it frees the care-giver to pursue other tasks away from the patient. Additionally, when the monitoring is done at a central facility a single nurse can monitor multiple patients which can result in decreased staffing requirements.
Generally speaking, electronic monitors work by first sensing an initial status of a patient, and then generating a signal when that status changes, e.g., he or she has sat up in bed, left the bed, risen from a chair or toilet seat, etc., any of which situations could pose a potential cause for concern in the case of an at-risk patient. Electronic bed and chair monitors typically use a pressure sensitive switch in combination with a separate monitor/microprocessor. In a common arrangement, a patient's weight resting on a pressure sensitive mat (i.e., a "sensing" mat) completes an electrical circuit, thereby signaling the presence of the patient to the microprocessor. When the weight is removed from the pressure sensitive switch, the electrical circuit is interrupted, which fact is sensed by the microprocessor. The logic that drives the monitor is typically programmed to respond to the now-opened circuit by triggering some sort of alarm--either electronically (e.g., to the nursing station via a conventional nurse call system) or audibly (via a built-in siren). Some examples of monitoring devices that operate in this general fashion may be found in U.S. Pat. Nos. 4,179,692, 4,295,133, 4,700,180, 5,633,627, and 5,640,145, the disclosures of which are incorporated herein by reference. Additionally, many variations of this arrangement are possible and electronic monitoring devices that track changes in other patient variables (e.g., wetness/enuresis, patient activity, etc.) are available for some applications.
However, present mats and other sensing devices for use in patient monitoring suffer from a number of disadvantages. For example, a problem with present mats and monitoring systems is that they do not provide a means for the monitor to identify the particular type of mat attached thereto. A monitor manufacturer might wish to do this for any number of reasons. For example, providers of medical equipment can be held liable for damages caused to a patient because of a failure in their monitoring system, a fact that argues for a method of making certain that mat attached thereto is fully compatible with the monitor.
Additionally, a monitor manufacturer would like to have some assurance that the mats that are attached to his or her unit meet basic standards of quality, as the monitor could blamed--at least initially--for a failure in a mat that allows a patient to leave the bed unnoticed. Further, for quality control purposes, it might be desired in some applications to be able to track the length of time that a particular mat has been in place, thereby assisting the health care provider in identifying mats that might be nearing the end of their useful lives.
Still further, it would be useful in some circumstances to be able to automatically identify whether the switch that is connected to the monitor is of the proper type for this application. For example, pressure-sensitive chair monitors should not be used to sense wetness in beds and vise versa. Where the possibility exists that the mats designed for different applications might be interchanged, it would be of benefit to the manufacturer of the mats and/or electronic monitors to be able to recognize that fact and notify the caregiver accordingly.
Finally, it is a problem with present mats and monitoring systems that they do not provide any means of automatically determining whether or not the electrical connection between the monitor and mat is sound. It is well known to those skilled in the art that the wiring that interconnects the mat and monitor is exposed to various stresses that can result in impaired functionality or even equipment failure. For example, if the interconnecting wire is not making continuous contact at one end or the other, the monitor will see an "open" circuit, whether or not the patient is actually present in the bed. To test the interconnection, it is necessary to put weight on the mat, which would usually be done by placing the patient upon it, thereby closing the detection circuit which event can then be sensed by the monitor. Where there is problem in the connection, the patient will have to be roused out of bed so that the mat can be changed. This disturbs the patient and takes additional caregiver time. It would be a tremendous advantage in some situations to be able to have the electronic monitor quickly and automatically indicate to the caregiver when there is there is no electrical continuity between the mat and the monitor.
Heretofore, as is well known in the bed monitor arts, there has been a need for an invention to address and solve the above-described problems. Accordingly, it should now be recognized, as was recognized by the present inventors, that there exists, and has existed for some time, a very real need for a smart mat and monitoring system that would address and solve the above-described problems.
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.